content: /*
   * Copyright 2011-2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package ix;
  
  import java.util.Iterator;
  
  final class IxSwitchIfEmpty<T> extends IxSource<T, T> {
  
      final Iterable<? extends T> other;
  
      IxSwitchIfEmpty(Iterable<T> source, Iterable<? extends T> other) {
          super(source);
          this.other = other;
      }
  
      @Override
      public Iterator<T> iterator() {
          return new SwitchIfEmptyIterator<T>(source.iterator(), other);
      }
  
      static final class SwitchIfEmptyIterator<T> extends IxSourceIterator<T, T> {
  
          final Iterable<? extends T> other;
  
          Iterator<? extends T> otherIterator;
  
          boolean nonEmpty;
  
          SwitchIfEmptyIterator(Iterator<T> it, Iterable<? extends T> other) {
              super(it);
              this.other = other;
          }
  
          @Override
          protected boolean moveNext() {
              Iterator<? extends T> ot = otherIterator;
              if (ot != null) {
                  if (ot.hasNext()) {
                      value = ot.next();
                      hasValue = true;
                      return true;
                  }
                  done = true;
                  return false;
              }
  
              if (nonEmpty) {
                  if (it.hasNext()) {
                      value = it.next();
                      hasValue = true;
                      return true;
                  }
                  done = true;
                  return false;
              }
  
              if (it.hasNext()) {
                  nonEmpty = true;
                  value = it.next();
                  hasValue = true;
                  return true;
              }
  
              ot = other.iterator();
              otherIterator = ot;
              if (ot.hasNext()) {
                  value = ot.next();
                  hasValue = true;
                  return true;
              }
              done = true;
              return false;
          }
  
          @Override
          public void remove() {
              Iterator<? extends T> ot = otherIterator;
              if (ot != null) {
                  ot.remove();
              } else {
                  it.remove();
              }
          }
      }
  }
  